Optical waveguides are presently being used for a number of applications including communications, interconnects between optical circuits, and certain optical resonator applications. For varying reasons, there are needs to have phase modulators associated with these optical waveguides. The phase modulators create selected phase shifts for any number of reasons. One particular instance where a phase modulator is necessary is in conjunction with an optical resonator. Additionally, there are numerous instances where phase shifts may be required, for example, in optical communication networks, or in conjunction with optical circuits.
Optical modulators of several types are presently used. Examples of these optical modulators include acousto-optic modulators, as well as electro-optic modulators. Acousto-optic modulators are devices wherein an acoustic wave traveling in a bulk medium is used to modulate an optical signal which is traveling in an associated medium. The disadvantage of acousto-optic modulators is their use of acoustic waves, or sound waves, which are fairly slow and require a large bulk medium to support their transmission.
Another type of modulator is a magnetic modulator. These modulators require the creation of some type of magnetic field which interacts with the optical signal traveling through the modulator. The interaction with the magnetic field alters the amplitude and/or frequency of the optical signal.
A third type of modulator is an electro-optic modulator wherein the optical signals interact with an electric field. The field interaction alters the characteristics of the optical signal, thus varying the frequency amplitude and/or phase of the optical signal.
All of the above-mentioned modulators require precise alignment of the differing components. Specifically, the modulator itself must be aligned and positioned to receive an incoming optical signal and must be situated to appropriately transmit an output optical signal. This alignment can often become very tedious and exacting work which is both time consuming and costly. Furthermore, the modulators require the use of specific materials (i.e., electro-optic materials, magnetic materials, and acousto-optic materials) which display the appropriate characteristics.
Also, many times the application of material on the modulators is uncontrollable. The composition as well as the amount of crystallinity has not been able to be controlled in the past. Further, in the magnetic modulators, the orientation of the magnetic axis of the material is poor and many times, improperly aligned which results in loss. It would be desirable to optimize the operation of the phase modulators by controlling material deposition and optimizing the alignment so that loss could be reduced as well.
It is an object of the present invention to provide a magnetic modulator and system of fabrication, such that the modulator exhibits very low losses and very high efficiency.
A further object of the present invention is to provide a system of fabricating a magnetic modulator which can be used in conjunction with the fabrication of other components on a single substrate. Specifically, it is an object of the invention to fabricate a magnetic modulator upon a substrate without destroying components which already exist on the same substrate.
Another object of the invention is to provide a system of fabricating a magneto-optic modulator which is capable of depositing the necessary thin films of magnetic materials.
The present invention provides a system for the fabrication of a magneto-optic modulator. The method can be used to easily and economically fabricate a magneto-optic modulator which is easily integrated into other devices. Furthermore, the present invention can be used to fabricate a modulator which is situated on a single substrate along with accompanying waveguides. The modulators fabricated are very efficient and high speed modulators. Furthermore, due to the materials used and the purity/consistency of the materials, very low power is required to achieve the necessary modulation.
In accordance with the above-mentioned goals and objectives, the magnetic modulator of the present invention is fabricated using the processes of ion beam and magnetron deposition. It is now possible to use these processes to fabricate thin films of magnetic materials having the necessary magneto-optic characteristics to form a magneto-optic modulator. The deposition processes can be used at differing points in the fabrication of optical devices because the deposition processes are non-destructive methods of fabrication. More specifically, these methods of thin film deposition can be used to fabricate films on a single substrate without destroying previously fabricated structures that already exist upon that substrate.